The invention relates to a method and apparatus for forming a flat panel display by combining a plurality of individual display devices.
The size of an individual display device such as a liquid crystal display (LCD) element typically is limited by acceptable manufacturing yields using currently known techniques. It would therefore advantageous to be able to combine several individual display devices together to produce either a larger display or to mount individual display devices in various positions on a larger display panel. For example, in the computer, television, and entertainment industries, large area displays of a size much larger than single display device sizes are desired for viewing by groups of people or single individuals.
In such applications, close placement and alignment of individual display devices to each other are critical parameters in order to make the edges of the display devices inconspicuous. That is, it is desirable to ensure no breaks are visible as information is viewed across the boundaries from display device to display device. Automotive and aircraft dashboard panels may require information such as speed, temperature, and fuel level to be displayed in various positions, sometimes with large gaps between these positions, on a large overall display panel.
One method of forming a display panel is to clamp individual display elements between two glass plates using screws or other tighteners and brackets of various design about the edges of the glass plates. Individual display elements may then be viewed through one of the glass plates. The display can be illuminated, if necessary, by placing a light source behind the second glass plate. Such a method is set forth, for example, in U.S. Pat. No. 4,156,833, the entire disclosure of which is hereby incorporated by reference.
Both the illuminating radiation (hereinafter referred to as xe2x80x9clightxe2x80x9d) as well as the display device image must, of necessity, pass through one or more of the glass plates. Optical properties of the glass plates (such as the transmission/absorption spectrum, and reflectance properties of both surfaces) are important design parameters that can affect display panel performance. These parameters can possibly cause reductions in brightness, contrast, and resolution. Consequently, it is important to select a glass material and surface treatment with care and to minimize the number of layers and interference surfaces through which the images and illuminating light must pass. Obvious variations of this overall structure are possible using optically transparent materials other than glass, such as various plastics, or even opaque materials, for the backplate in applications where reverse illumination is not needed.
Placing and holding individual display devices in accurate alignment prior to clamping the glass plates together has been difficult to achieve due to extremely precise requirements on alignment accuracy and the possibility of shifting one or more devices previously aligned as others are added prior to clamping all of these in place.
It is also beneficial to provide a seal to prevent dust, moisture, and/or other contaminants, from entering the display panel after assembly. Including a seal during clamping can add complexity and difficulty to the clamping process.
Various methods which are the subject of other patents have been developed for making electrical connection to each of the display elements, or for providing electrical interconnection between these. Connections can be made by overlapping edges of display elements as shown in U.S. Pat. Nos. 5,164,853 and 4,408,836 and Japanese patent JA 0302222, or by abutting corresponding conductive pads on edge surfaces of adjacent display elements as shown in U.S. Pat. No. 5,067,021. The entire contents of the four patents immediately above are hereby incorporated herein by reference. Any of the above or other connection schemes can be employed in the present invention.
It is an object of the present invention to provide a device for aligning and attaching a plurality of individual display devices to result in a larger display device.
Another object of the present invention is to provide a method for aligning and attaching a plurality of individual display devices utilizing the apparatus of the present invention.
An additional object of the present invention is to provide a system for assembling a flat panel display from a plurality of smaller display panels including a plurality of stations for carrying out various operations in the assembly process.
A further object of the present invention is to provide a method for assembling a flat panel display from a plurality of smaller individual display panels utilizing an apparatus including a plurality of stations for carrying out various steps in the method.
In accordance with these and other objects and advantages, aspects of the present invention provide a system for aligning and attaching together a plurality of thin film transistor tiles for constructing a flat panel display. The apparatus includes a coverplate loading station where a coverplate that the tiles are to be attached to is arranged on a coverplate support. At a coverplate bonding material dispensing station, a bonding material for bonding the tiles to the cover plate is applied to a surface of the coverplate. The tiles are arranged on the cover plate at a tile placement station. At a tile aligning and securing station, the tiles are aligned relative to each other and to the coverplate by a tile aligner. At the station, the tiles are also at least partially bonded to the coverplate. A bonding material is applied to a surface of the tiles opposite the side of the tiles that the coverplate is bonded to at a tile assembly bonding material dispensing station. At a backplate placement station, a backplate is arranged on the tiles. The backplate is aligned with the tiles and coverplate at a backplate aligning and securing station. At the backplate aligning and securing station, the backplate is also at least partially secured to the tiles. The tiles are fully bonded to the coverplate and the backplate at a full bonding station. The assembly of the coverplate, tiles and backplate is finalized at a final assembly output station. At the final station, the completed assembly may be prepared for transport to another operation and/or for storage until needed in a further operation.
Other aspects of the present invention provide a method of aligning and attaching together a plurality of thin film transistor tiles for constructing a flat panel display. According to the method, a coverplate that the tiles are to be attached to is placed on a coverplate support at a coverplate loading station. A bonding material is applied to the coverplate for bonding the tiles to the coverplate onto the coverplate at a coverplate bonding material dispensing station. A plurality of tiles are arranged on a tile support at a tile loading station. The tiles are connected to a tile aligner. The tiles are arranged on the coverplate at a tile placement station. Then tiles are aligned relative to each other and to the coverplate by the tile aligner and at least partially bonding the tiles to the coverplate at a tile aligning and securing station. A bonding material is applied to a surface of the tiles opposite the side that the coverplate is bonded to at a tile assembly bonding material dispensing station. A backplate is arranged on the tiles at a backplate placement station. The backplate is at least partially bonded to the tiles at a backplate aligning and securing station. The coverplate and the backplate are fully bonded to the tiles at a full bonding station.
Still other objects and advantages of the present invention will become readily apparent by those skilled in the art from the following detailed description, wherein it is shown and described only the preferred embodiments of the invention, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.